Tailoring the Luminescent Properties of SrS:Ce3+ by Sr-Deficiency and Na+ Doping.

Abstract

Ce3+-doped SrS phosphors with a charge-compensating Na+ addition were successfully synthesized via a solid-state reaction method, and the related X-ray diffraction patterns can be indexed to the rock-salt-like crystal structure of the Fm3̅m space group. SrS:(Ce3+)x (0.005 ≤ x ≤ 0.05) and SrS:(Ce3+)0.01,(Na+)y (0.005 ≤ y ≤ 0.030) phosphors were excited by 430 nm UV-Vis light, targeted to the 5d1 → 4f1 transition of Ce3+. The composition-optimized SrS:(Ce3+)0.01, (Na+)0.015 phosphors showed an intense broad emission band at λ = 430-700 nm. The doping of Na+ was probed by solid-state nuclear magnetic resonance. The 430 nm pumped white light-emitting diode structure fabricated with a combination of SrS:(Ce3+)0.01,(Na+)0.015 and Sr2Si5N8:Eu2+ phosphors shows a color-rendering index (Ra) of 89.7. The proposed strategy provides new avenues for the design and realization of novel high color quality solid-state LEDs.